1. Technical Field
The present invention relates to a projector that includes a light source, an optical modulator that modulates a light beam irradiated from the light source in accordance with image information to form an image and a projection optical system that projects the formed image.
2. Related Art
There have been known projectors that form an optical image in accordance with image information and project the optical image on a screen or the like in an enlarged manner. Among such projectors, there is known a projector that includes a light source, an optical modulator that modulates a light beam irradiated from the light source in accordance with image information and a projection lens that projects the modulated light beam as an optical image.
Recently, so-called three-panel projectors have been proposed, which can form an image with enhanced image quality and color reproducibility. Such a three-panel projector includes: a color-separating optical system that separates a light beam irradiated from a lamp as a light source into three color light beams of red (R), green (G) and blue (B); a plurality of liquid crystal panels as optical modulators which modulate the incident color light beams in accordance with image information; and a color-combining optical device that combines the color light beams modulated by the liquid crystal panels to form an optical image.
Note that it is necessary to uniformly illuminate an image formation area of an optical modulator such as a liquid crystal panel. Accordingly, there has been known a projector .with an integrator illuminating optical system that divides a light beam irradiated from the lamp into a plurality of partial light beams, superpose the partial light beams on the image formation areas of the optical modulators and uniformly illuminate the image formation areas (see, for example, JP-A-2005-234126).
The projector disclosed in the document includes as the integrator illuminating optical system a first lens array having a plurality of small lenses arranged in a matrix form, a second lens array having a plurality of small lenses respectively corresponding to the plurality of small lenses of the first lens array, a polarization converter that aligns polarization directions of light beams respectively irradiated from the plurality of small lenses of the second lens array and a superposing lens that superposes the incident light beams from the polarization converter on the image formation areas of the liquid crystal panels, each component being in a plane orthogonal to the optical axis of the light beam irradiated from the lamp. The integrator illuminating optical system uniforms a light amount on an illumination region of the light beam irradiated from the lamp, so that the image formation areas of the liquid crystal panels can be uniformly illuminated.
However, a light emitting portion of the light source lamp of such a projector may be moved from the middle of the electrodes of the light source lamp. When the light emitting portion is moved after optical components of the projector are positioned and fixed, a formed optical image may contain color unevenness.
To avoid the problem, there have been demands for a projector that can reduce luminance unevenness on the image formation area of the optical modulator even when the light emitting portion of the light source lamp is moved substantially from the middle of the electrodes after the positioning and fixation of the optical components.